Electrical socket for printed circuit cards



Sept. 12, 1961 u. TUCHEL 2,999,997

ELECTRICAL SOCKET FOR PRINTED CIRCUIT CARDS Filed April 22, 1958 IN VEN TO 26 Ulrich TUCHEL W xz socket. plate-shaped members having printed circuits thereon, are

2,999,997 I ELECTRICAL SOCKET FOR PRINTED CIRCUIT CARDS Ulrich Tuchel, Bismarckstr. 107, Heilbronn (Neckar),

Germany Filed Apr. 22, 1958, Ser. No. 730,074

Claims priority, application Germany Dec. 19, 1957 7 Claims. (Cl. 339-17) The present invention relates to contact strips of the type adapted to be inserted into a socket which is adapted to receive a flat counter contact carrier and to devices equipped with such contact strips.

It is well known in the prior art to utilize contact strips having a socket adapted to receive a flat counter contact carrier. Such strips are frame-like closed bodies formed of electrical insulation material and may be embedded in a closed frame shaped metal housing.

Within the framed bodies, electrical contacts are grouped either on one or on both elongated sides of the Such contact strips, for the connection of fiat of especial importance. The width and thickness of the socket opening of a closed, frame shaped contact strip ,had to exactly fit the dimensions of the counter contact carrier to be inserted therein in order to secure a perfect fit and an even contact pressure along the entire length of the contact strip. For each plate or other counter contact carrier of a certain thickness for insertion in a socket, it is necessary to use an exactly dimensioned and properly fitting counter contact strip. On account of the closed, frame-like shape of the device having the contact socket, it was necessary to stock strips of every required dimension, said strips being made in various lengths to accommodate the different applications.

It is therefore an object of the present invention to provide means facilitating a radical reduction of the number of strips of different dimensions required to be stocked.

Another object of the invention is to provide means conducive to a highly economical, simplified and efficient contact strip construction, which may consist either of separate members or which can be formed as a directly connected part of a printed circuit unit.

Another object of the invention is to provide means affording a contact strip structure formed of complementary parts, only one of which needs to be provided with contacts so that the other part can serve as a form determinant, guide and contact pressure controlling counter cuit units.

These and other objects of the invention will become i further apparent from the following detailed description,

reference being made to the accompanying drawing showing a preferred embodiment of the invention.

In the drawing:

FIG. 1 is a perspective view of an assembly comprised of a plurality of printed circuit units provided with releasable contact connector devices pursuant to the pres- United States Patent 2,999,997 Patented Sept. 12, 1961 ent invention, the various parts of the assembly being illustrated in disassembled relation;

FIG. 2 is an exploded perspective view, on an enlarged scale, of a female contact connector shown in FIG. 1; and

FIG. 3 is a fragmentary detail view illustrating a modified form of male contact connector.

Referring now to FIG. 1 of the drawing in detail, there is shown a printed circuit unit 1 constituted by a card or plate 1' formed of insulation material which constitutes a support or carrier for printed circuits (not illustrated) which can be provided therein in any well known manner. As shown, the plate 1' is provided, at a marginal edge thereof, with a rectangular cut-out or recess 2. A casing half 3, formed of suitable insulation material, overlies the cut-out 2 at the lower surface of plate 1', and a complementary casing half 4, formed of insulation material, overlies the cut-out at the upper surface of the plate 1.

The casing halves are provided with aligned mounting apertures 5 adapted to receive rivets or other securing elements which extend through the plate 1 to securely mount the casing halves to the opposite surface thereof, so as to define a socket or receptacle 2 at the cut-out. The casing halves are each formed of insulating material. Casing half 3 is devoid of electrical contacts but casing half 4 is provided with the contacts or contact elements 6 which are disposed within the socket 2 so that the latter constitutes a female electrical connector. It will be understood that the pin-like projections 17 of contact elements 6 are electrically connected in conventional fashion to any printed conductive paths provided on plate 1. The width of the socket 2 is determined by the separation of the opposing edges 40-41 of the cutout 2 and the depth thereof is determined by the interconnecting edge 42 of the cut-out.

A printed circuit unit 8, constituted by a card or plate 8 provided with the printed conductive paths 10, is provided with a rectangular projection 9, which is complementary to the cut-out 2 and is dimensioned to interengage or interfit therewith.

The terminal portions 10 of the printed circuits 10, disposed on the upper surface of the projection 9, form electrical contacts or contact elements thereon so that the projection 9 constitutes a male contact connector adapted to be releasably engaged in the female contact connector or socket 2 so as to effect the electrical connection of the contacts 6 and .10 when the projection 9 is inserted into the socket. It will be understood that the terminal portions 10' are suitably reinforced to serve as contact elements or counter-contacts for the contacts 6.

From the foregoing, it will be apparent that the contact holding strips or casing halves 3-4 can either be separate members, as shown, which are secured to the plate 1', or be formed as part thereof. The plate 1 forms a spacer or wedge between the contact brackets and the cut-out 2 therein provides a guide for the insertion of the projection 9 into the socket 2. Furthermore, the plate 1' itself defines the width of the socket, by virtue of the cut-out 2, when the casing halves are secured thereto. This enables the projection 9 on a plate or circuit carrier 8', of equal thickness to the plate 1', to fit into the socket.

The printed circuit unit 8 is provided with several rows of guide apertures 11 defined in the plate 8, only one row being illustrated in the drawing. Provision is made for a pair of casing halves 3' and 4, similar to the previously described casing halves 3 and 4, respectively, and provided with aligned apertures 5 similar to the apertures 5. Rivets 43 may be used to secure the casing halves 3 and 4 together, as in the case of the casing halves 3 and 4, so that the brackets 34' form a contact strip similar to the contact strip formed by the casing halves 3-4. The brackets 34' define a socket 13 similar to the socket 2'. The width of socket 13 is determined by a U-shaped spacer or wedge plate 12 disposed in the space between the casing halves and provided with apertures for the rivets 43. Casing half 4' mounts contact elements 6', within the socket13, which contact elements 6 are provided with pin-like projections 17 which extend outwardly of the assembled casing halves and are adapted to fit into a row of the holes 11. i

The holes 11 can be provided with metallic bushings (not illustrated) by inserting hollow rivets therein. It will be understood that the rivets or bushings are suitably electrically connected with the printed circuits 10. The projections 17 are dimensioned to project from the lower surface of the plate 8, when inserted in the holes 11, so that they can be dip-soldered to the metallic bushings or rivets.

Provision is made for another wired circuit unit 15 constituted by an insulation card or plate 15 provided with the printed circuits or conductive paths 16;. The plate 15 is provided with a rectangular projection 14 adapted to fit into the socket 13. The terminal portions 16' of the printed circuits 16 form terminal or counter contacts for effecting electrical contact with the contacts 6' when the projection 14 is removably inserted in the socket 13. i

When projection 9 of plate ST is inserted into the recess 2 of plate 1, the printed circuit unit 3 is disposed flush with the printed circuit unit 1. ,By plugging the projections 17 from the casing halves 3l into the holes 11 in the printed circuit unit 8, the contacts 6" of said casing are electrically connected to the printed circuits 10. The printed circuit unit 15 can then be mounted normal to the interconnected units 1 and 8, by inserting the contact bearing projection 14 into the socket 13, so that the conductive paths of the unit 8 now effect electrical connection between the printed circuits provided on the plates 1' and 15'.

As shown in FIG. 1, only the casing halves 4 and 4' are provided with contacts. However, it will be understood that the opposing casing halves 3-3' can also be provided with contacts, so that printed circuits on both sides of the contact units may be accommodated by associated contacts in the contact strips defined by' the paired sets of paired casing halves.

By adding additional rows of mounting apertures 11 in the plate 8', additional printed circuit units 15 may be mounted on the base panel 8'. The distances between the units 15 would be determined by the thicknesses of the contact strips defined by the sets of easing halves 34' if no other electrical elements are mounted on the panels 15'. It required, brackets 3'4 may be mounted on the panel 15', in the same manner as described in connection with the panel 8'.

The casing halves 3-3, which mount no contacts, are provided with ribs 7 which are disposed in opposition to the contacts Ger 6', as the case may be, on the casing halves 4 and 4', as best shown in FIG. 2. The contacts 6 and 6' are inserted in cavities 22 defined by reinforcements 21 provided on the respective casing halves and these contacts are each constituted bythe paired arms 23-24 which are formed of spring metal and are interconnected within the cavity 22. The arms are hook shaped being similarly bent in the same direction. The front edges 25 of the paired arms 23-24 extend in the direction of insertion of the rectangular projections 9 and 14 into their associated sockets soasto make contact with associated counter contactsprovided on said projections.

The arms 23 and 24 are subdivided, in conventional manner, by transverse slots, which define spring biased tongues 28', each of which has a front edge 28" which extends in the direction of insertion .of the counter contacts provided on the panel projections. Each pair of arms 2324 is provided with the previously described 4 projection 17, which is in the form of a small tube which terminates in a bevel shaped end 26 to facilitate its insertion into a hole 11. The described construction of the contacts 6' also provides the advantage that by means of the described projection 17 the rivets or sleeves provided in the holes 11 can be inserted in the holes vertical to the strip and can be connected without reduction of the creep distance or air gap. If the contact 6' terminated in the flat shape of a soldering lug, then the wire to be connected thereto would have to be inserted from the side. This would have the disadvantage that such a connection would come too close to the other contacts on either side thereof and therefore would not provide a good insulation therefrom.

In assembling the parts shown in FIG. 2, the mounting holes 18 of casing half 3', the holes 19 of the spacer or wedge plate 12 and the holes 20 of easing half 4 are aligned and rivets 43 are inserted therein to interconnect said parts and form the socket 13 which receives the rectangular projection 27 of a wired circuit unit provided with counter contacts (not illustrated) or other circuit elements, for contact with the front edges 25 of the spring contact elements 23-24 of the contacts 6 provided .in the casing half 4.

Pursuant to the modification shown in FIG. 3, in order to establish a good contact connection, the projection 9 of the counter contact panel 8, is provided with the terminal ends 29 of the printed circuits 10. The terminal ends 29 are reinforced with contact wipers, clips or studs 30 which ar formed of thin metal foil, about as wide as the printed circuit terminals 29, and bent about the front marginal edge 32 of the flat counter contact panel 8'. A rivet 31 secures the wiper 30 tightly against the printed circuit path and establishes a good electrical connection therebetween. This construction is of special advantage where high contact pressure is required.

Where the printed circuit terminals 10' or 16 arefrequently plugged into and out of the associated socket, the terminals, being formed of a thin metal coating, will be subjected to relatively great strains or pressures and may tend to peel or rub ofi. The use of wipers 30 will prevent such deleterious results. In lieu of rivets 31, the wipers 30 may be affixed in any other suitable manner, or by soldering or dip-soldering.

In view of the foregoing, it will be apparent that in the form of the invention shown in FIGS. 2 and 3, the contact strip is split lengthwise and a wedge or spacer plate is inserted between the two parts thereof.

The thickness of the spacer plate accommodates to the overall inner dimensions of the socket formed in the contact strip which is dimensioned to accommodate the flat counter contact member to be inserted therein. The dimensions of the separate contact strip elements are such that when the elements are connected together they form the smallest socket that may be needed. All other necessary dimensions in the width of the socket will be formed by inserting a wedge or spacer plate of suitable thickness in between the strip elements.

The design and shape of the contact strips makes it .possible to equip only one of the casing halves with contacts, so that theother one serves as a form or shape determinant, a guide and .a contact pressure limiting counter holder, or both casing halves can be, provided with contacts. In the first case it is of advantage that the-casing half is used as a counter holder, on the very spot which is located opposite the points of contact on the other casing half, for the purpose of attaining a minimum ofimechanical friction, this being obtained through the use of serrations or ribs, which in this way determine the width of the socket for flat counter contact carriers. In the second case it is of advantage to design the spaces for mounting the contacts in the one casinghalf in such a manner that when both casinghalves are assembled to the plate of a wired circuit unit, said spaces are in oif-set or staggered relation.

In this way, space for twice the number of contacts can be provided by the same dimensions of the contact strips. The electrical contacts fitting into the brackets can be made of any 'kind of arbitrary shape. These contact engage counter contacts inserted into the socket and provide a minimum of electrical contact resistance since they are formed of spring metal and have at least two contact face-edges which extend parallel to the direction of insertion of the counter contacts and said spring contacts can be divided into a plurality of spring tongues which are hook shaped and paired. Such contacts can be inserted into the cut-outs of the casing halves which form the contact strips so that the distances between the contacts will be determined by the electrical requirements.

A contact strip, suitable for a layered assembly of a plurality of printed circuit units, can be made with the contacts projecting through the contact strip on the side opposite their insertion therein, and terminating preferalbly as a pointed or bevel-shaped tube forming shell electrically connected to the circuit units. It is possible to insert such a contact strip into the socket of another contact strip of a circuit unit underlying the first unit, if the underlying unit is equipped with elements suitable to receive the pin-like projecting ends of the contacts. 7 With the described contact strips, more than two panel shaped circuit units, normal to each other, can be plugged together, each unit having printed circuits on either one Or both surfaces thereof. In this way it is possible that electrical aggregates, each of which can form a constructional unit of intricate design, can be easily detached and accurately assembled together, especially where one of the interconnected parts is defective. The faulty part can be easily removed without disturbing any of the other sections. The faulty part can be replaced or repaired or reinserted into the assembly. It is possible to interlock various assemblies so that only the correct assemblies can be reinserted into the correct positions.

The casing halves of the contact strips can be formed with hollow sections for the insertion of the contacts so that the wall thicknesses at said sections are reduced to save raw material and the gain in the overall wall thickness will be very little. The casing halves of the contact strips can be formed of an insulating plastic material or by molding or spraying. The plates which mount the counter contacts are preferably provided with printed circuits and can be used to connect a single building element, or 'a soldering lug, or a terminal strip for the connection of wires or cables.

The casing halves of the contact strips can be manufactured in multiples of a desired length of use and the desired length can be cut from the original strip. Also, the use of very long contact strips is rendered possible whereby the security and stiffness of the attachment is always constant on account of the minimum length determined for the attaching distances.

Various changes and modifications may be made without departing from the spirit and scope of the present invention and it is intended that such obvious changes and modifications be embraced by the annexed claims.

Having thus described .the invention, what is claimed as new and desired to be secured by Letters Patent, is:

1. A socket comprising a pair of complementary casing halves, a spacer element interposed between said casing halves in secured relation therewith and determining the widthwise dimension of said socket, electrical contacts provided within said socket on one of said casing halves, said socket having an entrance opening at one side thereof, said contacts each having a pin-like projection extending from said socket at the opposite side thereof, said one casing half having cavities defined therein extending rear- 6 wardly from said entrance opening, said contacts being mounted in said cavities, said contacts being formed of spring metal and each having a pair of complementary hook-shaped arms provided with contact edges extending rearwardly from said socket opening.

2. The socket of claim 1, wherein said arms are slotted transversely thereof to define a plurality of paired hookshaped tongues.

3. An assembly comprising a pair of complementary casing halves formed of electrical insulating material and defining a socket therebetween, contacts provided within said socket on one of said casing halves, means secured between said casing halves for defining the dimensions of said socket, said means comprising a member formed of insulating material, a panel disposed in contact with said casing halves opposite the socket opening, said panel having conductive paths printed thereon, said panel having apertures therethrough in alignment with said paths, 2. plurality of electrically conductive projections connected to said contacts and depending from said casing halves and extending into said apertures securing said casing halves to said panel with the dimension-defining portions of said member extending between said casing halves to define said dimensions, the other of said casing halves having a ribbed surface confronting said contacts with a rib opposed to each contact.

4. A female socket for receiving a printed circuit panel having a plurality of individual printed circuits comprising a panel having a substantially rectangular cutout portion adapted to receive a projected portion of the printed circuit panel, socket wall means of insulation material extending around the marginal edge of the cutout portion and overlying each side of the cutout portion and defining a socket receptacle surrounding the cutout portion, a plurality of individual contact members spaced along the cutout portion held at one end in said socket wall means and extending toward the cutout area for efiecting contact with the individual circuits of the printed circuit panel when the latter is inserted therein.

5. A female socket according to claim 4, wherein said contact members extend through said socket wall means to the exterior thereof for connection exteriorly of said socket wall means.

6. A female socket according to claim 4, wherein said contact members include a central eyelet portion held in said socket wall means and separate resilient leg portions extending from said eyelet portion into the cutout portion to provide spaced resilient contact legs therein.

7. A female socket according to claim 4, wherein said contact members are secured to an upper wall of said socket wall means and the opposite wall is provided with a plurality of ribbed portions for the purpose of directing the printed panel upwardly against the contact members when the printed panel is positioned in said socket.

References Cited in the file of this patent UNITED STATES PATENTS 2,566,805 Lavander Sept. 4, 1951 2,881,404 Kamm Apr. 7, 1959 2,891,229 Flanagan June 16, 1959 FOREIGN PATENTS 648,076 Great Britain Dec. 28, 1950 725,032 Great Britain Mar. 2, 1955 OTHER REFERENCES Buggie PC Catalog, January 8, 1954, page 3.

Circon Application Notes C-lOl Nov. 1, 1954 (1 page).

Winsker et al., Electronic Design, Sept. 15, 1957, pp. 104-5. 

